I know this applies for bumguns —various water boards have published guidance— but a lot of the under-seat bidets retract [without positive water pressure].
There's no risk of the spout sitting in and siphoning dirty toilet water it back into your supply. I'm neither a lawyer or a plumber but these seem like they might be okay.
Nah, in the UK it's now fairly uncommon to still have a hot water tank. Most houses have mixer taps, and new fittings for bathrooms or kitchens will have mixer taps unless the home owner is masochist.
The separate taps thing is more because it costs to replace a sink. So even if you put a new boiler in an old houses lots of people aren't going to replace the fittings in the kitchens and bathrooms at the same time.
> There's no risk of the spout sitting in and siphoning dirty toilet water it back into your supply
In many places in Europe tap water is safe to drink. However, hot tap water is not.
The regulations mentioned by GP might protect safety of the cold tap water from intake of hot tap water. Which is easy to do unintentionally when mixing hot and cold water.